Original subtitles

- [Narrator] Our history is no more than

a series of incredible events.

Each one of us can influence its course.

The tiniest of our decisions

can influence the future of mankind.

To know the past is to anticipate the future.

April, 1939.

At the dawn of the second world war,

Nazi Germany launches the secret uranium project.

August 2, 1939.

Albert Einstein, renowned physicist,

signs a letter to the president of the United States.

August 6, 1945.

An American B-29 bomber drops an atomic bomb

on the city of Hiroshima.

These three intimately connected events

are the key moments of the Manhattan Project

and will lead to the end of the second World War.

(dramatic music)

Germany, February 28, 1933.

The Reichstag, seat of the German parliament.

(liquid splattering)

In the middle of the night,

men break into the building and start a devastating fire.

Recently appointed chancellor, Adolf Hitler,

immediately accuses the Communists and bans their party.

This is the age of financial crises,

of Nazi Germany, and the second World War.

Inexorably, the Nazis take over power

and impose their racist ideology.

According to them, Germany belongs to the Aryans,

the people they define as a pure race.

The rest are stripped of their basic freedoms.

Persecutions follow.

Those with the resources flee the country

for more welcoming shores.

Among them are many intellectuals, artists, and scientists,

and also nuclear physicists.

At the time, German science is the global benchmark.

Between 1901 and 1933,

23 Nobel Prizes are awarded to German citizens.

However, seven of them will flee the Reich

because of political and ethnic cleansing.

And so, Nazi ideology deprives Germany

of some great physicists, especially Albert Einstein,

who goes into exile in the United States in 1933.

In 1938, things escalate.

Hitler annexes the Sudetenland,

a territory with many Germans,

but also with the largest uranium mine in Europe.

Hitler doesn't stop there,

and the following year he invades Bohemia and Moravia.

These conquests deliver the entire uranium reserves

stocked in Prague.

The armies of the Reich

are determined to conquer the whole of Europe.

To stop Hitler, the United Kingdom and France

declare war on Germany.

It's the start of the second World War.

- [Narrator] Welcome to the memory of humanity.

Here we can control time,

analyze and compare billions of events

and alter them to rewrite history endlessly.

(dramatic music)

For example, let's imagine that Nazi Germany

had succeeded in building one, or several,

nuclear weapons in 1943.

Its use would certainly have been psychological.

Cities would have been the priority targets.

Stalingrad, the Russian city,

and symbol of Germany's first major defeat,

would have been the first to be wiped off the map.

Then Moscow, and finally London.

We can even imagine a modified U-boat submarine

surfacing in New York Harbor with a nuke on board.

The world would have been left stunned

by the power of the Reich.

Not knowing the number of bombs at the Nazi's disposal,

a ceasefire would've been signed immediately.

Germany would've won the war.

The world would then have toppled into a cold war

between the two great powers,

the United States and the Third Reich.

Our world would be tragically different.

Let's take a look at the course of events.

- [Narrator] The second World War is a total war.

On all fronts, between all peoples, with all weapons.

Each camp relies on ingenuity to destroy its adversaries.

Each camp fears the enemy will discover the ultimate weapon.

The Allies know that Germany is conducting

a secret program to build the nuclear bomb,

the Uran Project.

When they invade Norway,

the Nazis got their hands on

the only European plant capable of producing heavy water,

indispensable for the production of the bomb.

The scientists who fled Germany

are convinced that the Nazis are near their goal.

The United Kingdom is also conducting an atomic program,

but its resources are monopolized by

the defense of it's own coasts.

If the Nazis get the bomb before the Allies,

the fate of the world is sealed.

The results of the English research

are sent to the United States,

the only country capable of rivaling Germany

financially and industrially.

However, on the other side of the Atlantic,

the priority is to remain neutral,

far away from the conflict.

They are not interested in a bomb with a hypothetical power.

They prefer conventional weapons that are real.

On August 2, 1939, Einstein, world-renowned physicist,

signs a letter addressed to the President

of the United States, Franklin Roosevelt.

Einstein is a confirmed pacifist,

but for him, nuclear technology must not fall

into the wrong hands at any price.

So, he rings the alarm bell

to force the United States to react.

In his letter, Einstein explains to Roosevelt

that scientists are within a hair's breadth

of knowing how to build a nuclear bomb.

He adds that Germany is well placed to get there first.

Roosevelt at once decided to create

a committee on uranium.

History had just taken a major turn.

- [Narrator] We have just reached a turning point.

A turning point is a key event,

a crossroads in our history,

where the world swings one way or the other.

Einstein has just alerted President Roosevelt

to the danger posed by the atomic bomb

if it falls into the wrong hands.

At once, Roosevelt creates a committee on uranium.

What would've happened

if Einstein had not signed that letter?

We can suppose that the program

would still have been conducted,

but not with the same energy or the same sources.

It would've been just one program among others.

When the end of the war came,

the United States would've been a long way

from possessing a working bomb.

The enormous costs, justified in time of war,

are no longer so in time of peace.

Congress would certainly have dropped the military program

to pursue the civil nuclear.

As for the Soviet Union,

it would probably have recovered all the Nazi research

and material left by the Americans

and carried out it's own secret program.

In the 1960s, to general surprise,

the Russians would have carried out a nuclear test

by exploding the first atomic bomb in history.

The United States could only calculate

how far they were behind.

The United States, up til then a super power,

would wake up to a world dominated by the Soviet Union.

- [Narrator] This December morning in 1941

brings a harsh wake up call to the American Pacific forces.

(air raid siren blaring)

(bombs exploding)

With the surprise attack on Pearl Harbor,

the Japanese Empire has just declared war

on the United States.

The conflict becomes a planetary one.

In the United States, the Committee on Uranium

created by Roosevelt, gradually turns into a

top secret nuclear physics research program

and then a real industrial program.

They now call it the Manhattan Project.

General Leslie Groves, appointed head of the program,

has access to virtually unlimited funds.

He recruits a brilliant scientist

to the post of Scientific Director,

Robert Oppenheimer.

Their mission, develop an operational atomic bomb

before the Nazis.

The race is on.

Groves quickly realizes that this is an industrial task

on a vast scale.

They have to build plants from scratch,

recruit a large work force,

and employ experienced managers.

Spread out over secret locations throughout the country,

the Manhattan Project's 32 sites

are soon running at full speed.

At Oak Ridge, on a base eight miles wide

by 17 miles long, they produce uranium,

the explosive material of the first bomb.

At Hanford, which then becomes

the third largest city in the state of Washington,

they manufacture plutonium for the second bomb.

On the highly protected base of Los Alamos,

in the middle of the desert,

a high-tech laboratory builds the actual bombs.

With a budget almost equivalent to $26 billion today,

the Manhattan Project is incontestably

one of the biggest programs of the second World War.

130,000 people are mobilized, supervised,

and guarded in secrecy.

The work is highly compartmentalized.

Few people know the final aim of the operation.

Everything is done to ensure

the objective is achieved on time.

However, on May 8th, 1945,

after fierce resistance, Germany abandons the fight.

But the program is not halted.

On the contrary, because Japan is still there.

Groves orders his teams to push the nuclear plants

to the maximum, to the limits of safety standards.

Even though Japan has virtually no chance

of developing a nuclear weapon,

building the bombs is an absolute priority.

July 16, 1945,

5:29.

The Trinity Test, the first nuclear explosion in history.

With the power equivalent to 20,000 tons of TNT,

it was heard up to 200 miles away.

The United States becomes the first nuclear power.

- [Narrator] The atom.

So small, so harmless.

And yet, some have a special capacity.

They can split in two.

This is what is known as nuclear fission.

When bombarded by neutrons, these atoms split.

They then release an enormous amount of energy,

and more importantly, neutrons,

which go on to split more atoms.

This is a chain reaction.

When the atoms are sufficiently numerous

and close to one another,

the chain reaction doesn't stop,

it becomes an explosion.

Certain atoms are particularly suited for this process;

uranium and plutonium.

The Manhattan Project produces two types of bomb

in parallel.

Little Boy is an atomic bomb three meters high

with a payload of uranium.

Fat Man, the more powerful of the two,

is equipped with plutonium.

Developed later, during the 50s,

H bombs, or thermonuclear bombs,

don't rely upon fission, but upon nuclear fusion.

They are horrifically more powerful.

The first atomic bomb was equivalent to 20,000 tons of TNT.

In 1961, the Russians test the Tsar thermonuclear bomb.

Equivalent to 57 million tons of TNT.

- [Narrator] The atom bomb is a devastating weapon.

It was built to reverse the course of the war.

But in August, 1945, Germany has already surrendered

and Japan is in constant retreat

before the power of the United States.

The war is won.

It is now only a question of time.

American factories have turned out aircraft carriers

by the dozen, planes by the thousands.

Like Germany before the Soviet steamroller,

Japan can no longer reverse the situation.

And yet the Japanese are determined to fight

to the last man.

Marines confront fanatical Japanese soldiers.

The tiniest atoll is won at a very heavy cost.

The Emperor's soldiers prefer death to surrender.

Kamikaze pilots deliberately fly into enemy ships.

Each inch of ground is defended.

At the beginning of 1945,

American naval forces are close enough

to the Japanese coast to begin a systematic bombardment

of cities and industries.

The invasion of the archipelago's main islands

is planned but the operation is risky.

The Japanese Army still numbers nearly 2,300,000 men.

This final battle would exact an enormous toll

in human life on both sides

and neither side wants another year of war.

They want to finish it.

The idea is to break Japan's will to resist.

To strike it psychologically,

to force it to surrender.

The atomic weapon appears like a ready-made solution.

Truman has replaced Roosevelt as president.

He has several options.

Drop one of the two bombs on a desert region

to show Japan its power, or

strike a Japanese city following an ultimatum.

Neither solution is adopted.

The United States only possesses two bombs.

There can be no question of wasting one,

and you don't spend billions of dollars

to blow up a desert.

On July 24, Truman signs the order

to carry out nuclear raids.

Only July 26, Japan receives

the final ultimatum to surrender.

But the Japanese hesitate.

On the one hand, the Americans are imposing

unconditional surrender on them, an unacceptable solution.

On the other hand, the Soviets may allow them

to salvage their honor.

They need to buy more time.

Their hesitation is interpreted by the Americans

as a refusal.

The United States will now be able to demonstrate

their brand new power to the world.

- [Narrator] Death comes from the sky.

Little Boy weighs 4 1/2 tons.

It requires a heavy bomber to carry it.

The B-29 appointed for the mission

has been named Enola Gay.

For safety reasons, the 16-kiloton bomb

is armed in flight.

The plane must not descend below an altitude of 30,000 feet.

At 8:15 a.m. and 17 seconds,

the bomb is dropped over Hiroshima

and its 350,000 inhabitants.

The fall lasts 43 seconds.

During this time, the bomber must get eight miles away

if it is to survive.

At 2,000 feet above the ground,

Little Boy's pressure sensors

trigger the conventional explosives

that create the nuclear chain reaction.

A giant flash blinds anyone looking at it

without protection.

Everything within a radius of two miles disintegrates.

At the epicenter, the temperature reaches

11,000 degrees Fahrenheit,

destroying everything around it.

Just after the explosion, the heat dilates the air,

causing over pressure and an enormous blast effect

that spreads at 500 miles per hour.

Air pressure at the center collapses in an instant.

The rush of air reverses.

The mushroom, sucking in dust and debris,

begins to rise and reaches a height of 50,000 feet.

It is laden with highly radioactive dust

that falls as a black rain on the survivors.

70,000 people die in one second.

During the months that follow,

the number of deaths will rise to 140,000.

The city is wiped off the map.

- [Narrator] Hiroshima is no more.

Japan still doesn't surrender.

Three days later,

the second nuclear bomb if dropped on Nagasaki.

American calculations were correct.

Killing more than 100,000 civilians with just two bombs

intimidates Japan sufficiently

for it to resolve to accept the inevitable.

On August 15, 1945, the Empire surrenders

to the Americans.

(dramatic music)

The second World War is over.

Together the Allies have succeeded in

overcoming their enemies.

But the apparent cohesion conceals growing dissension.

The Soviet Union and the United States

have become too ideologically opposed super powers.

Even before the end of the war,

frictions are clearly visible.

During the conflict, the Allies realize

the major importance of scientific research.

From 1943, Russian secret services had been obtaining

precious information on the Manhattan Project,

which drove Stalin to launch his own nuclear program.

With Germany defeated, the Allies fight over

the remains of German Uran Project.

The Alsos Mission is a special branch

of the Manhattan Project.

It's objective is to recover what they can

before the Soviets reach Germany.

Conducted in the form of commando raids,

the Alsos Mission made it possible to recover

secret documents, valuable equipment,

and above all, many German scientists.

Study of this information will show that

the Nazis were, in fact, not very far advanced

compared to the Manhattan Project.

They would not have been able to produce nuclear weapons

for several years.

However, this was the main reason

that drove the United States to develop the atomic bomb.

Einstein will never forgive himself

for having contributed to the creation of this weapon.

In 1955, at the age of 76, he will confess,

"I made one great mistake in my life,

"when I signed that letter."

Several years later, hugely assisted by

the dismantling of German installations

and the nuclear spy network.

The Soviet Union will carry out its first test.

Since then, eight other countries

have acquired atomic weapons.

Formally allies, the United States and the Soviet Union

will enter a race to nuclear armament.

It's the start of the Cold War.

But that is another story.

- [Narrator] Total war.

During its Civil War, the United States applied the concept

of waging war by every means.

The method doesn't matter, but you must win.

During the second World War,

this principle is widely applied by both camps,

right up until the final hours of the war.

In Germany, for example, the cities of Dresden and Hamburg

are destroyed by massive Allied bombing.

70,000 people die, burned by incendiary bombs

dropped night and day by thousands of bombers.

In Japan, Tokyo is literally peppered with bombs.

There are 100,000 dead.

Legally, this is not yet a war crime.

We must wait until 1949 and the Fourth Geneva Convention

for civilians to be protected by law in times of war.

It's difficult to know what the Nazis would have been

capable of if they had had the bomb.

Fortunately, Hitler's fanaticism brought about

his own destruction.

But in the end, history has taught an important lesson.

No matter in whose hands they may be,

these weapons of mass destruction are terribly dangerous

and must be controlled.

Einstein did not want Hiroshima.

He simply hoped to prevent a terrible apocalypse.

And sure enough, humanity is still here.